Immunoassay Of Carcinoembryonic Antigen (CEA) Based On Electrochemiluminescence Of Quantum Dots And CdS Film Synthesised By Electrodeposition

In chapter one of this thesis, we reviewed the electrochemilumineseence (ECL) and its application in immunoassay in the recent years. Firstly, we gave a brief introduction about the defination of ECL and its development history. Based on the relationship between the ECL intensity and the concentration of the antigen or antibody under test, we divided its application in immunoassay into two modes of enhancement and quenching. In the immunoanalysis, we gave a simple classification of the ECL materials which served as the markers, mainly including Ru(bpy)32+, luminol, and their derivates which were most widely used in the enhancement ECL immunoassay as well as the quantum dots used in the quenching ECL immunoassay. Finally, we also collected, classified and gave a brief introduction of the recent progress and result in ECL immunoassay.In the chapter two, we researched the ECL of a new semiconductor nanocrystal (quantum dots) on modified electrode. In the experiment, we immobilized the quantum dots capped with thioglycolic acid on the surface of modified electrode by the covalent bond. With potassium persulfate as the coreactant, we detected the ECL emission when scaned from 0 to-2 V. In addition, we labled quantum dots on the sandwich immunocomplex for the detection of carcinoembryonic antigen (CEA) because the intensity of the ECL of quantum dots reflected the quantity of CEA immobilized on the electrode. Moreover, we introduced a new nanomaterial-nanoporous gold leaf to modify the electrode, which could effectively increase specific surface area of the electrode, enhance the current signal of electrode in solution, and greatly improve the sensitivity of the immunoanalysis. Using this method, a linear relationship between IECL and the CEA concentration is obtained in a range of 0.05 to 200 ng/mL.In the chapter three, we study a new method of quantum dot preparation. That is electrodeposition. In the electrolytic solution composed of CdSO4/Na2S2O3/EDTA, CdS films could be electrodeposited on the electrode via cyclic potential scan between 0 to-1.2 V. which could also show strong ECL emission with potassium persulfate as the coreactant. So we designed a new kind of immunoanalysis method on CdS film modified electrode and based on the quench effect of the immunoreaction on ECL, the CEA concentration was determined in the range of 0.01 to 200 ng/mL.